I've tried measuring her weight in the past and felt that our postal scale didnt do her justice; she once went through a noticeable growth spurt and weighed the same afterwards, so I felt like it wasn't accurate. I can try again though, so I can more accurately figure out what size mouse she should be eating. I'll just have to put her in something smaller to maybe distribute her weight more accurately.
I used to feed her two fuzzy mice approximately once a week. And by "approximately" I mean "pretty much always once a week unless I forgot in which case I'd adjust accordingly but put her back on the same schedule the next week". I would heat the mice by soaking them in hot water (hot to the human touch, but not enough to cook/burn or anything) and let them sit from after dinner to when I feed her when I go to bed, which can be anywhere from 11 pm to 3 am. My mom's wondered if that was the issue, but we tried feeding her in less time yesterday (still a few hours though, like one or two) and it didn't make a difference. Letting the mouse dry out doesn't affect it either, and I don't know if scent could be an issue considering she doesn't care about if the mouse is bleeding or not, but I'm not sure.
We have one of those pet store thermometers (it came with our reptile setup kit we bought, which I'm sure I can find the exact name for if I looked) sitting on the ground near the hot end of her tank. It's supposed to be on the wall but it keeps falling off so we just leave it there lol.
The room she's in gets to be around 74 - 78 F, possibly lower but I don't think it ever gets below 70 unless we turn on her heater. I generally close the window around a half an hour to an hour (or more) before I turn off her light, so that it won't get any colder in the room. She's in the far corner from the window as well, but the 78 temperature is the temperature in the enclosed hallway (not where she is) and >74 is in the room she's in (but in the direct path of the open window) so... It's probably not 78 since the hallway is one of the hottest parts of our house, but it might not be as low as our other thermometer either, im not sure.
Also I should mention that I got her to eat a fuzzie last night
I pestered her enough with it and she finally ate it. I'd rather not have to harass her with a mouse every night though because I can tell she doesn't enjoy it so my issue still stands, but at least I don't have to worry about her starving herself to death. (Well I'll still worry but XD)